JP 2011-97693 A (hereinafter referred to as “Patent Document 1”) discloses a conventional power supply system for a vehicle in which two DC power supplies are connected in parallel to an electric power line, via respective converters. In this power supply system, one of the DC power supplies is controlled by voltage and the other DC power supply is controlled by electric power by a feedback control such that the electric power requested from a motor (load) is supplied by the combination of these two DC power supplies. Further, in the power supply system, an electric power target value which is set to the other DC power supply in accordance with an electric power distribution ratio is compensated in accordance with a deviation between an electric power command value requested to this DC power supply and an actual electric power value which is actually input and output. Patent Document 1 describes that, in this way, stable power management can be achieved because the influence (such as overdischarging and overcharging) of the DC power supply caused by the deviation between the actual electric power and the electric power command value can be eliminated.